1. FIELD OF THE INVENTION
This invention relates to novel S-substituted-2-thioadenosines useful as a platelet aggregation inhibitor and a coronary vasodilator.
2. DESCRIPTION OF THE PRIOR ART
It is well known that a certain type of S-substituted-2-thioadenosines exhibit a vasodilating activity as reported in M. H. Maguire et al., Journal of Medicinal Chemistry, Vol. 14, p. 415 (1971); J. A. Argus et al., British Journal Of Pharmacology, Vol. 41, p. 592 (1971); and R. Einstein et al., European Journal of Pharmacology, Vol. 19, p. 246 (1972). Also, it is well known that some S-substituted-2-thioadenosines possess a platelet aggregation inhibitory activity as reported in G. V. R. Born et al., Nature, Vol. 205, p. 678 (1965); F. Michael et al., Nature, Vol. 222, p. 1073 (1969); and M. A. Packham et al., American Journal of Physiology, Vol. 223, p. 419 (1972). Typical examples of such S-substituted-2-thioadenosines are 2-methylthioadenosine-5'-monophosphate disclosed in U.S. Pat. No. 3,781,274 and 2-lower-alkylthioadenosines disclosed in U.S. Pat. No. 3,752,805. However, the 2-methylthioadenosine-5'-monophosphate exhibits only a weak platelet aggregation inhibitory activity and the 2 -lower-alkylthioadenosines have almost no platelet aggregation inhibitory activity.
Recently, a series of S-substituted-2-thioadenosines having improved platelet aggregation inhibitory activities and coronary vasodilating activities has been found as disclosed in U.S. Pat. Application Ser. Nos. 378,116, filed on July 10, 1973, now U.S. Pat. No. 3,919,194, 378,117, filed on July 10, 1973, now U.S. Pat. No. 3,910,883 and 371,340, filed on June 19, 1973, now U.S. Pat. No. 3,910,884.